The secure transmission of computer files via communication means has increased in importance with the proliferation of the Internet for electronic distribution and electronic commerce. The fundamental shift from physical delivery of computer files and/or computer programs to digital based electronic transmission has commenced with the Internet emerging as a ubiquitous low cost network. As in previous technological advancements such as the transition from newspaper to radio and then to television, media companies of the time were forced to react to the emergence of these new mediums. However, unlike previous technological transitions, the Internet as a medium supports all of the functionality of the traditional print, radio and television industries while simultaneously supporting electronic commerce as well. Currently, many businesses utilize the Internet to sell or give away their computer files and/or computer programs via the Internet and in most cases, the computer files are not encrypted for protection against piracy or illegal use. Additionally, the current approach relating to the secure transmission and storage of computer files fails to leverage encryption functionality of a computing device's operating system. The current approach calls for a computing device acting as a server (the “Serving Device”) to communicate with another computing device acting as a client (the “Client Device”) to transfer encrypted files for decryption at the application level (such as, but not limited to, Win32 Application) of the Client Device. The Client Device utilizes a computer program running at the application level for decryption, which is assigned a unique decryption “key.” During the transmission process, the Serving Device encrypts the computer file for storage using the decryption “key” of the Client Device. The encrypted computer file is then transmitted via the Internet and saved into storage within, or connected to, the Client Device. After decryption of the computer file, the decrypting computer program transmits a decrypted signal to the operating system for display or, in the case of an audio file, playback through the sound card. The decrypted signal can be vulnerable when transmitted from the decrypting application to the operating system, and the signal can be intercepted, possibly resulting in the illegal duplication of the computer file.
Addressing certain aspects of computer file and computer program encryption, the Microsoft Corporation published in 1998, a white paper titled “Microsoft Windows NT version 5.0, Public Key Infrastructure”, incorporated by reference herein, (hereinafter the “Windows 2000 PKI White Paper”), detailing encryption functionality of a comprehensive public key infrastructure (PKI) in the Windows 2000 family of operating systems (formerly referred to as Windows NT 5.0). The Windows 2000 PKI White Paper stated on the cover page thereof, “Microsoft® Windows NT® version 5.0 introduces a comprehensive public key infrastructure (PKI) to the Windows® platform. This utilizes and extends the Windows-based public key (PK) cryptographic services introduced over the past few years, providing an integrated set of services and administrative tools for creating, deploying, and managing PK-based applications. This allows application developers to take advantage of the shared-secret security mechanisms or PK-based security mechanism in Windows NT as appropriate. At the same time, enterprises gain the advantage of being able to manage the environment and applications based on consistent tools and policy mechanisms.”
Furthermore, and with special emphasis on the encryption functionality of the Public Key Infrastructure of the Windows 2000 family of operating systems, the Windows PKI White Paper stated, “The Web has rapidly become a key element in creating and deploying solutions for the effective exchange of information on a worldwide basis. In particular, growth in its use for business purposes has been dramatic. For many uses, security is a key consideration. Notably: Server authentication—To enable clients to verify the server they are communicating with. Client authentication—To allow servers to verify the client's identity and use this as a basis for access control decisions. Confidentiality—Encryption of data between clients and servers to prevent its exposure over public Internet links.
The Secure Sockets Layer (SSL) and the emerging IETF standard Transport Layer Security (TLS) protocols play an important role in addressing these needs. SSL and TLS are flexible security protocols that can be layered on top of other transport protocols. They rely on PK-based authentication technology and use PK-based key negotiation to generate a unique encryption key for each client and/or server session. They are most commonly associated with Web-based applications and the HTTP protocol (referred to as HTTPS).
SSL and TLS are supported on the Windows platform by the secure channel (schannel) SSPI provider. Microsoft Internet Explorer and Internet Information Services both use schannel for this functionality. Because schannel is integrated with Microsoft's SSPI architecture, it is available for use with multiple protocols to support authenticated and/or encrypted communications.
Taking full advantage of the SSL and TLS protocols requires both clients and servers to have identification certificates issued by mutually trusted CAs, allowing the parties to authenticate each other. In this mode, certificates are exchanged along with data that proves possession of the corresponding private key. Each side can then validate the certificate and verify possession of the private key using the certificate's public key. The identifying information included in the certificate can then be used to make supplemental access control decisions. For example, the client can decide whether the server is someone it wishes to conduct business with and the server can decide what data the client will be allowed access.
The Windows NT 5.0 PKI integrates support for the latter decisions as a standard feature of Windows NT Server. User certificates can be mapped on a one-to-one or many-to-one basis against security principals (User objects) in the Active Directory. Schannel can take advantage of this information to automatically synthesize a security token for the client such that the Windows NT ACL mechanisms are used to enforce access control to resources. This is advantageous for services in that they can utilize the identical access control mechanism independent of the client authentication mechanism used (PK or Kerberos).
Once the client and server have authenticated each other, they can proceed to negotiate a session key and begin communicating securely. SSL and TLS are also often employed in a mode that doesn't require client authentication. Use of mutual authentication is recommended in the enterprise environment, however, because it allows you to make use of the Windows-based access control mechanisms. Also, the PKI significantly simplifies certificate enrollment and management, reducing the burden on the client.”
In another white paper published by the Microsoft Corporation in September 1998, titled “Windows NT Workstation 5.0 Key Benefits and Capabilities Whitepaper”, incorporated by reference herein, (the “Windows 2000 Workstation White Paper”) Microsoft provides additional detail on encryption functionality of the Windows 2000 family of operating systems. The Windows 2000 Workstation White Paper stated on page 30 thereof, “Windows NT Workstation 5.0 provides support for Public Key security, an industry-standard authentication protocol used over public networks, such as the Internet. The most important use of Public Keys is for digital signatures, which assure authenticity of components, including that: E-mail came from the sender; E-mail cannot be viewed or edited by other users; Applications and drivers come from known sources; Software is protected from tampering after installation; The identity of a remote computer is guaranteed; Secure Internet communication is allowed; Strong encryption is allowed, such as that needed for secure transactions.
While other platforms, such as any Windows platform running Internet Explorer 4.0, support the use of Public Keys, Windows NT Workstation 5.0 goes further by providing a more robust infrastructure for creating certificates, “trusts” with other systems, and secure storage for certificates.”
The Windows 2000 Workstation White Paper expands on secure virtual private network services, stating on page 31 thereof, “In addition to PPTP, today's most common method, Windows NT Workstation 5.0 supports several new, more secure methods of creating Virtual Private Networks, including: L2TP (Layer 2 Tunneling Protocol), a more secure version of PPTP, for tunneling, address assignment, and authentication; IPSEC (IP Security Protocol), a standard-based protocol that provides the highest levels of VPN security. With IPSEC, virtually everything above the networking layer can be encrypted. This provides end-to-end privacy, integrity, and authenticity over public networks. The IPSEC method is transparent to applications and protocols. Microsoft is working closely with vendors to support hardware acceleration for IPSEC through NDIS interfaces.
Windows NT Workstation 5.0 also provides an enhanced Network Connections dialog that makes it easier for users to create VPNs (see the “Simplicity” section).”
Additionally, Microsoft discusses storage encryption functionality within the Windows 2000 family of operating systems in the Windows 2000 PKI White Paper, describing an encrypting file system (EFS) which resides in the Windows 2000 kernel. Microsoft states in the Windows 2000 PKI White Paper on pages 21 and 22 thereof, “The Windows NT 5.0 Encrypting File System (EFS) supports transparent encryption and decryption of files stored on a disk in the Windows NT file system (NTFS). The user can designate individual files to encrypt, or folders whose contents are to be maintained in encrypted form. Applications have access to a user's encrypted files in the same manner as unencrypted files. However, they will be unable to decrypt any other user's encrypted files.
EFS makes extensive use of PK-based technology to provide mechanisms for encrypting files to multiple users and well as supporting file recovery. To do this, it utilizes the ability of PK to support bulk encryption without prior shared secrets. In operation, each EFS user generates a public key pair and obtains an EFS certificate. The certificate will be issued by an enterprise CA in the Windows NT 5.0 domain, although EFS will generate a self-signed certificate for stand-alone operation where data sharing is not an issue. In addition, Windows NT 5.0 supports an EFS recovery policy in which trusted recovery agents can be designated. These agents generate an EFS recovery public key pair and will be issued an EFS recovery certificate by the enterprise CA. The certificates of the EFS recovery agents are published to domain clients with the Group Policy Object.
In operation, for each file to be encrypted EFS creates a random key that is used to encrypt the file. The user's EFS public key is then used to encrypt this secret key and associate it with the file. In addition, a copy of the secret key, encrypted with each recovery agent's EFS public key, is associated with the file. No plaintext copy of the secret key is stored in the system.
When retrieving the file, EFS transparently unwraps the copy of the secret key encrypted with the user's public key using the user's private key. This is then used to decrypt the file in real time during file read and write operations. Similarly, a recovery agent may decrypt the file by using the private key to access the secret key.”
Providing additional detail on the level of security of Microsoft's Encrypting File System, the Windows 2000 Workstation White Paper states on page 28 thereof, “An Encrypted File System (EFS) encrypts files on a hard disk. Each file is encrypted using a randomly generated key, which is independent of the users' public and/or private key pair. EFS resides in the Windows NT kernel and uses the non-paged pool to store file encryption keys, ensuring that they never reach the paging file. EFS is supported on a file or directory basis. Encryption and decryption is transparent to the user.”
The instability of computing functions (such as, but not limited to, functions resulting in computing system crashes) is generally regarded as greater at the application level than at the operating system level. The closer the computing functions are to the core of the operating system, the more stable they are generally. If an application level decryption program becomes damaged or corrupted and reinstallation of another decryption program is required, a new “decryption key” is generated and the previously encrypted computer files, being encrypted to the old “decryption key,” cannot be decrypted by the newly installed decryption program. Avoiding the encryption and/or decryption weaknesses inherent in application level programs, Microsoft has taken steps to protect lost “encryption and/or decryption keys” in the Windows 2000 PKI. Microsoft stated in the Windows 2000 PKI White Paper on page 14 thereof, “Public key pairs and certificates tend to have high value. If they are lost due to system failure, their replacement may be time consuming and result in monetary loss. To address these issues, the Windows NT 5.0 PKI supports the ability to back up and restore both certificates and associated key pairs through the certificate-management administrative tools.”